(3R*,6R*,4′S*,8′R*,3′′R*,6′′R*)-3,3′′-Diisopropyl-6,6′′-dimethyl-2′,6′-diphenyldispiro[cyclohexane-1,4′-(3,7-dioxa-2,6-diazabicyclo[3.3.0]octane)-8′,1′′-cyclohexane]-2,2′′-dione

The two oxazolidine rings (A and B) of the title compound, C34H44N2O4, display roughly half-chair conformations, which could be described as twisted on the C—O bond. Together, the fused oxazolidine rings have a butterfly shape, with the H atoms attached to the ring junction C atoms in a cis orientation. The cyclohexane rings of both p-menthone fragments display chair conformations. The absolute configuration could not be determined from the X-ray diffraction data, but the relative configuration of the stereocentres could be deduced.

The two oxazolidine rings (A and B) of the title compound, C 34 H 44 N 2 O 4 , display roughly half-chair conformations, which could be described as twisted on the C-O bond. Together, the fused oxazolidine rings have a butterfly shape, with the H atoms attached to the ring junction C atoms in a cis orientation. The cyclohexane rings of both p-menthone fragments display chair conformations. The absolute configuration could not be determined from the X-ray diffraction data, but the relative configuration of the stereocentres could be deduced.  (2004). For related structures, see: Iball et al. (1968Iball et al. ( , 1986; Aurich et al. (1989). For ring conformations, see: Cremer & Pople (1975 Synthesis of various p-menthane derivatives is studied extensively, with the goal to obtain biologically active and ecofriendly corrosion inhibitor compounds (Ito et al., 2009;Kharchouf et al., 2011;2012;Majidi et al., 2010). p-Menthan-3-one, 1 (Menthone) have become the key starting natural compound for the synthesis of a number of substances exhibiting various kinds of biological activity (Ito et al., 2009). Menthone, a monoterpene ketone, occurs in nature and is widely present in high concentration in a few Mentha species, such as Mentha specata aromentha (Clark, 1990), M. Avrvensis (Umemoko, 1998) and the essential oils of pepperimint and other mint oils (Boelens, 1993). On the other hand, isoxazolidine rings are the frame of a number of natural products and antibiotics and are extensively used in the synthesis of a great many biologically important compounds (Wagner et al., 2004). The goal of the present study was to obtain a new p-menthane derivative having two isoxazolidine moieties. This latter is of interest, because it can exhibit biological activity and has useful properties as precursor for synthesis.
To a mixture of 6 mmoles of 2-hydroxymethylene menthone and 6 mmoles of n-diphenylnitrone in 20 ml of ethyl acetate ( Fig. 2) was added a catalytic amount of K 10 (montmorillonite/FeIII). The reaction mixture was stirred for 48 h at 25°C and then filtered. The solvent was removed and the product was purified by recrystallization in ethanol (yield 67%).
Single cristals were obtained by slow evaporation of an ethanol solution at room temperature.
supplementary materials

Refinement
In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined, so any reference to the Flack parameter was removed.

Computing details
Data

Figure 1
Molecular view of the title compound with the atom labeling scheme. Ellipsoids are drawn at the 30% probability level.
H atoms are represented as small spheres of arbitrary radii.

Figure 2
Scheme showing the synthetic pathway T min = 0.908, T max = 1.000 24309 measured reflections 5963 independent reflections 3751 reflections with I > 2σ(I) Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.